(1.) Field of the Invention
This invention is concerned with a method of positioning two workpiece portions for stitching together along a desired stitching path, and more particularly a method of using a pallet to position portions of a shoe upper for stitching.
(2.) Summary of the Prior Art
In many instances, especially in using automatic sewing machines, it is conventional to utilize a so-called pallet by which two workpiece portions to be stitched together can be first positioned in a desired overlapping relationship and then be clamped in such relationship prior to being presented to stitching instrumentalities of a sewing machine. One such pallet is described in U.K. Patent Specification No. 1473687. Such a pallet is provided with a base portion having a slot corresponding to the desired stitching path, workpiece positioning means by which a first workpiece portion can be positioned with the region, corresponding to the desired stitching path, thereof in alignment with the slot, while the workpiece portion is in a substantially flat condition, and second workpiece positioning means whereby a second portion, also in a substantially flat condition, can be positioned, in superposed relationship with the first portion, and with its region, corresponding to the desired stitching path, in alignment with the slot, the two workpiece portions being clamped together by appropriate clamp means in such alignment.
In the manufacture of certain workpieces, however, e.g. the manufacture of shoes, it often arises that the regions of the two workpiece portions do not overlap over the whole of their length when the workpiece portions are in a substantially flat condition; that is to say, in joining the workpiece portions together, it is desirable to take into account the final three-dimensional shape of the finished article. It will be appreciated that, under such circumstances, a pallet of the type referred to above will not normally be able to be used for the positioning of the two workpiece portions for the stitching operation to be performed thereon. On the other hand, it is most desirable that, where two workpiece portions are to be stitched together as aforesaid, they are accurately positioned in the regions to be stitched, in order to ensure the quality of the finished article.
It is therefore the object of the present invention to provide an improved method of positioning two workpieces for stitching together along a desired stitching path, said workpiece portions each having a region corresponding to said stitching path, which regions do not overlap along the whole of their length when the workpiece portions are in a flat condition, in carrying out which method the operator can nevertheless accurately position the regions of each workpiece portion in an overlapping relationship in which it can be clamped during the stitching operation.